Valve system for an arc extinguishing chamber and circuit breaker comprising same

Abstract

A closing system for an arc extinguishing chamber of a circuit breaker with high breaking capacity has been developed. The system according to the invention comprises a first duct equipped with a set of filters able to support usual pressures caused by the gases arising from the switching arc, in particular about 10 to 12 bars, and a second duct closed by a valve device enabling direct outlet of the exhaust gases when the pressure exceeds a threshold so as to prevent any explosion of the case. The outer wall of the extinguishing chamber is designed for the circuit breaker housing so as, including in case of opening of the valve device, to direct the gases and to prevent any arc-over on the frame. The valve device comprises a suitable membrane made from polymer, in particular aramide.

The invention claimed is: 
     
       1. An outer wall of an arc extinguishing chamber, for resting on two rims of a housing of the case of a switchgear unit, said outer wall comprising
 an external rigid grate for closing off said housing, said grate comprising an intermediate part and an end part for resting on said rims and for protruding from the intermediate part into a space defined between said wall and said rims, 
 a valve device coupled to the grate at the level of the intermediate part, including lips protruding from the intermediate part on at least two sides for resting on said rims, wherein said lips are heat-resistant insulating material having a strength such that each lip is substantially rigid and flat when said lip is subjected to an orthogonal pressure lower than a first threshold pressure, and said lip is deformable in reversible manner when the orthogonal pressure is greater than a second threshold pressure; and 
 an internal frame and a filtering system housed between the internal frame and the external grate, the valve device for forming a tight gasket between said frame and said grate, wherein a cross-section of the wall forms a T-shape the branches of which are for resting on said rims, and wherein the lips are of such a size that an orthogonal pressure on said lips will close a space defined where the branches of said T approach a flat side of said housing. 
 
     
     
       2. The outer wall according to  claim 1  wherein the second threshold pressure is 10 bars and the first threshold pressure is lower than 10 bars. 
     
     
       3. The outer wall according to  claim 1  wherein the valve device comprises a unitary shield having at least one central passage hole, the two lips being on two opposite sides of the hole. 
     
     
       4. The outer wall according to  claim 1  wherein the lips are made from polyaramide withstanding temperatures of more than 2000° C. for at least 5 ms. 
     
     
       5. The outer wall according to  claim 4  wherein the lips are made from polyamide, amides of which are separated by metaphenylene groups. 
     
     
       6. The outer wall according to  claim 1  wherein the second threshold pressure is 10 bars and the first threshold pressure is lower than 10 bars, wherein the lips are made from polyamide, amides of which are separated by metaphenylene groups, and wherein the valve device comprises a unitary shield having at least one central passage hole, the two lips being on two opposite sides of the hole. 
     
     
       7. The outer wall according to  claim 2  wherein the lips are made from polyaramide withstanding temperatures of more than 2000° C. for at least 5 ms. 
     
     
       8. An arc extinguishing chamber comprising a set of parallel arc separators, two side plates securing the separators, and an outer wall according to  claim 1  orthogonal to the side plates and to the separators, the lips of the valve device being located along the side plates. 
     
     
       9. An arc extinguishing chamber according to  claim 8  wherein the second threshold pressure is 10 bars and the first threshold pressure is lower than 10 bars and wherein the lips are made from polyaramide withstanding temperatures of more than 2000° C. for at least 5 ms. 
     
     
       10. An arc extinguishing chamber to  claim 9  wherein the valve device comprises a unitary shield having at least one central passage hole, the two lips being on two opposite sides of the hole, and the lips are made from polyamide, amides of which are separated by metaphenylene groups. 
     
     
       11. A switchgear unit comprising a case provided with at least one substantially rectangular parallelepipedic housing, comprising at least two of partitions which open out from the case with a rim, at least one separable contact pole-unit in said housing, and an outer wall according to  claim 1  resting on the rims to close said housing. 
     
     
       12. A switchgear unit comprising a case comprising at least one substantially rectangular parallelepipedic housing, comprising at least two partitions which open out from the case with a rim, and an arc extinguishing chamber according to  claim 8  in said housing resting on the rims. 
     
     
       13. The outer wall according to  claim 1  wherein the second threshold pressure is 10 to 12 bars, and the first threshold pressure is lower than the second threshold pressure. 
     
     
       14. The arc extinguishing chamber according to  claim 8  wherein the second threshold pressure is 10 to 12 bars, and the first threshold pressure is lower than the second threshold pressure. 
     
     
       15. An arc extinguishing chamber comprising a set of parallel arc separators, two side plates securing the separators, and an outer wall orthogonal to the side plates and to the separators, said outer wall for resting on two rims of a housing of a case of a switchgear unit, wherein the outer wall comprises:
 an external rigid grate for closing off the housing, said grate comprising an intermediate part and a T-shape having branches for resting on the rims and a central portion for insertion into a space defined by said rims; an internal frame and a filtering system housed between the internal frame and the external grate, a valve device for forming a tight gasket between said frame and said grate, coupled to the grate at the level of the intermediate part and lips protruding from the intermediate part on at least two sides for resting on said rims and along the side plates, wherein said lips are heat-resistant insulating material having a strength such that each lip is substantially rigid and flat when said lip is subjected to an orthogonal pressure lower than a first threshold pressure, and said lip is deformable in reversible manner when the orthogonal pressure is greater than a second threshold pressure, wherein the lips are of such a size that an orthogonal pressure on said lips will close a space defined between the grate and a flat side of the housing. 
 
     
     
       16. The arc extinguishing chamber according to  claim 15  wherein the lips are made from polyamide withstanding temperatures of more than 2000° C. for at least 5 ms, amides of which are separated by metaphenylene. 
     
     
       17. A switchgear unit comprising a case having at least one substantially rectangular parallelepipedic housing which comprises two partitions each of which opens out from the case with a rim, and an arc extinguishing chamber, and which comprises: a rigid grate for closing off the housing by resting on two rims of the housing, an intermediate part of the rigid grate being in a space defined by said rims; and a valve device coupled to the grate at the level of the intermediate part and lips protruding from the intermediate part on at least two sides for resting on said rims, wherein said lips are heat-resistant insulating material having a strength such that each lip is substantially rigid and flat when said lip is subjected to an orthogonal pressure lower than a first threshold pressure, and said lip is deformable in reversible manner when the orthogonal pressure is greater than a second threshold pressure; and
 an internal frame and a filtering system housed between the internal frame and the external grate, the valve device for forming a tight gasket between said frame and said grate, wherein a cross-section of the wall forms a T-shape the branches of which are for resting on the rims, and wherein the lips are of such a size that an orthogonal pressure on said lips will close a space defined between the grate and a flat side of said housing. 
 
     
     
       18. The switchgear unit according to  claim 17  wherein the second threshold pressure is 10 bars and the first threshold pressure is lower than 10 bars, wherein the lips are polyaramide withstanding temperatures of more than 2000° C. for at least 5 ms, the device forming a valve comprises a unitary shield provided with at least one central passage hole, the two lips being on two opposite sides of the hole. 
     
     
       19. The arc extinguishing chamber according to  claim 15  wherein the second threshold pressure is 10 to 12 bars, and the first threshold pressure is lower than the second threshold pressure. 
     
     
       20. The switchgear unit according to  claim 17  wherein the second threshold pressure is 10 to 12 bars, and the first threshold pressure is lower than the second threshold pressure.